Xinlonghongshan: a model of glacial alpine Danxia

01 The white snow simplifies the world and highlights the brightness of Danxia

Danxia landform is a type of landform "discovered" and named by Chinese geologists. It is mainly distributed in China's southern humid areas, northwest arid areas, and the Sichuan Basin in the southwest.

Sichuan is one of the three major Danxia landform distribution areas in my country, but Sichuan's Danxia landform is mainly distributed in the southwestern edge of the basin at the junction of Sichuan, Guizhou and Chongqing. The type is mainly a "hidden" Danxia where "cliffs are visible but peaks are not". Because of the widespread development of circular cliffs, it is also called "cliff Danxia".

Before the discovery of Hongshan in Xinlong County, there had never been any record of Danxia landforms being discovered on the western Sichuan Plateau. Therefore, when the Ase Danxia in Xinlong County was discovered, it attracted the attention and research interest of many scholars. It actually somewhat overturned our traditional understanding of the distribution of Danxia.

▲Danxia covered with the first snow. Photo by Yang Jian

It takes about 3 hours to drive from Xinlong County to Ase Danxia. We were worried about the weather all the way. It seemed that the sky was teasing us. The clouds were hanging low along the way, and it was threatening to snow and rain. When we arrived at Yinduo Township where Ase Danxia is located, it was already foggy and snowy.

The car stopped at the end of the road and we walked upwards. Miraculously, the weather cleared up. After we went around a mountain top, a large area of ​​red rocks suddenly appeared between the clouds.

The Red Mountain in the snow field has a unique beauty. The light snow newly covering the mountain and the drifting and dispersing fog make the Danxia landform, which is "as red as cinnabar and as bright as the clouds", look extremely enchanting.

Before coming here, I have read a lot of pictures and videos of Hongshan, and I have always felt that Hongshan in the snow is the most charming. The white snow simplifies the earth and makes the Danxia more pure and bright. This timely light snow seems to have fallen specifically for us.

▲Danxia covered with the first snow. Photo by Mi Hongwei

02 Affected by the action of glaciers, the Danxia here is "peaked and slanted"

Danxia landform is a "red-bed landform with steep cliffs". Material composition, geological structure, and external dynamic geological action (water erosion, gravity collapse, etc.) are often regarded as the three most important elements in the formation of Danxia landform.

The red rocks that make up the Ase Danxia were formed in the Paleogene of the Cenozoic Era about 65 million to 230 billion years ago. During that period, the Hengduan Mountains had escaped the invasion of the ocean and uplifted to become land. The Indian Plate was drifting northward from the south and collided with the Eurasian Plate, causing the entire plateau to rise sharply. In the early Cenozoic Era, the Ase area was located in a mountain basin with rivers and lakes. A set of thick red layers mainly composed of conglomerate and sandstone were deposited in the basin. They are the main scenic rocks that formed the Ase Danxia.

This set of rocks is relatively rough, poorly consolidated and relatively weakly resistant to weathering. As a result, it is often difficult to see steep cliffs and continuous cliff walls in the Ase Danxia, ​​which is very different from the Danxia landform formed by the Cretaceous red sandstone and mudstone on the edge of the Sichuan Basin.

▲The thick red layers mainly composed of conglomerate and sandstone are the main rocks that form the Ase Danxia. Photo by Mi Hongwei

Generally speaking, horizontal rock strata are more likely to form cliffs. However, due to the influence of the Himalayan orogeny, the rock strata in the Ase area are generally tilted and gently folded, which does not have the conditions for forming large cliffs.

Therefore, we can see that the shape of Danxia landform is also different here. It mainly develops macroscopic landscapes such as linear mountains, castle-like hills, stacked slate walls, monocline peaks, solitary peaks, etc. In addition, there are also some small and microscopic landforms, such as columnar stone peaks, isolated stone pillars, bamboo shoot-shaped stone buds and other microscopic pictographic rocks.

In particular, the mountains here are distributed in a linear manner and undulate, and the peaks are mostly cone-shaped and pyramid-shaped, showing the "atypical" Danxia characteristics of "top and sloping body", which is completely different from the "standard" Danxia landform of "flat top, steep body and gentle foot" that we see in Danxia Mountain in Guangdong.

▲Half of it is red mountain and half is trees. The distribution area of ​​Hongshan Danxia has a humid climate, dense rivers and streams, lush vegetation and beautiful environment. Photo by Mi Hongwei

The Ase Danxia is closer to the Danxia in the arid areas of Northwest China in terms of form. For example, a unique Danxia form is developed here - the sandstone window lattice palace structure, which is a unique Danxia landform in the arid areas of Northwest my country. It is named because its facade resembles a window lattice and its overall structure is like a palace. For another example, some cliffs are distributed with various holes formed by salt weathering, which are as big as Buddha niches and as small as honeycombs. This is also a common micro-landform on Danxia cliffs in the arid areas of Northwest China.

However, the Danxia landform in the arid area of ​​Northwest China is developed in an arid and rainless environment, with dry climate, sparse vegetation, and characteristics of desert and bad land. The Ase Danxia distribution area has a humid climate, dense rivers and streams, lush vegetation, and beautiful environment. Especially in summer, the green grasslands, forests and shrubs, rivers and lakes and the exposed red Danxia rocks complement each other.

▲A unique Danxia landform is developed here - sandstone window lattice palace structure, which is a unique Danxia landform in my country's arid and semi-arid areas. Photo by Mi Hongwei

03 Will the glacial-eroded alpine Danxia become a new type of Danxia?

Going upstream along the wide and gentle U-shaped river valley formed by the glacier, you can see mountains undulating like lines in the distance, strange peaks like forests nearby, rocks like clouds, green grass under your feet, gurgling streams, and the air is filled with the faint smell of cow dung and the fragrance of flowers and plants after the rain. It is a very pleasant sightseeing experience.

When we walked to a rock, Cai Huaye, Vice President of National Geographic China magazine, pointed ahead and asked me, "Is that an ancient cirque?" I looked up and saw a chair-shaped terrain surrounded by rock walls on three sides and open to the outside on the upper part of the mountain. It was indeed an ancient cirque.

Ancient cirques are a typical glacial erosion landform. Before they were formed, they were depressions that stored ice and snow. Glacial ice was formed here and then overflowed to form valley glaciers. After the glacier disappeared, the armchair-shaped landform transformed by the glacier became the ancient cirque.

Ancient cirques are common on the Qinghai-Tibet Plateau and are often used to determine the altitude and period of ancient glacier distribution. The accumulated water in ancient cirques often forms "cirque lakes". These small lakes are small in size, but exquisite and elegant, with the color of emerald sapphire. They are often distributed in groups between snow-capped mountains and meadows, with a kind of otherworldly beauty. Cirques are common, but this is the first time I have seen a cirque formed in the Danxia landform. Its appearance really surprised me. Cai Caiye jokingly called it "the first cirque in Danxia".

▲Ancient cirque in Ase Danxia. Photo by Jiang Xi

The appearance of the cirque reminded me of a polished surface of a glacier that I had seen on the way into the gorge. In fact, this kind of polished surface can be seen everywhere in the scenic area, as well as those cone-shaped and pyramid-shaped Danxia peaks and knife-like ridges. Aren’t these the horns and ridges formed by glacial action?

In the Ase Danxia area, there is also a more peculiar glacial relic - Shanyuan Stone Mountain, which is distributed in the middle and upper parts of the mountain. The peaks are sharp and cone-shaped, surrounded by ice and steep slopes. At first, it was thought to be Danxia stone pillars, but after careful comparison, it was confirmed.

▲Ice field rocks. Photo by Mi Hongwei

Glacial rock is a solitary mountain with its top exposed to the ice. It is a common glacial erosion phenomenon in continental glaciers, but it is rare to see it in the Xinlong Ase Danxia in the mountain glacier action area.

The overall altitude of Ase Danxia is mostly between 4,200 and 5,100 meters. There are more than ten peaks over 5,000 meters in the Danxia distribution area. This place is not only a typical high-altitude Danxia landform, but also an ancient glacial area during the Quaternary glacial period that ended about 10,000 years ago.

▲Columnar peak. Photo by Mi Hongwei

At that time, the glaciers here were winding and raging, and the glaciers were constantly eroding and transforming the landforms here. Professor Peng Hua and Professor Yin Jicheng seemed to have overlooked this point when they were looking for the differences in Ase Danxia. Water erosion is traditionally considered to be the main external geological effect in the formation of Danxia landforms, but the Danxia here is at a high altitude and has experienced glacial action. Glacial erosion not only participated in the shaping process of Danxia landforms, but is also very likely the main cause of the formation of Danxia landforms here.

Perhaps with the continuous deepening of scientific investigation and research here, a new type of Danxia landform may really emerge in the future. We will call it "glacial erosion type high-altitude Danxia landform" for the time being.

Uplift, leveling, sedimentation, fracture, water cutting, glacial erosion... Ase Danxia is a lucky one of the evolution of time. The unique red rock strata, complex geological structure, and persistent erosion by water and glaciers have "carved" out this largest plateau Danxia landscape in China. The story of rock and time is so wonderful.

▲Glacier drift in the river valley. Photo by Mi Hongwei

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References:

Li Zhongdong, “Ganzi Strange Stones: Red and Black”, China National Geographic Special Issue on Ganzi Prefecture, June 2022